Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
  • A61F2/02—Prostheses implantable into the body
  • A61F2/14—Eye parts, e.g. lenses, corneal implants; Implanting instruments specially adapted therefor; Artificial eyes
  • A61F2/16—Intraocular lenses
  • A61F2/1613—Intraocular lenses having special lens configurations, e.g. multipart lenses; having particular optical properties, e.g. pseudo-accommodative lenses, lenses having aberration corrections, diffractive lenses, lenses for variably absorbing electromagnetic radiation, lenses having variable focus
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
  • A61F2/02—Prostheses implantable into the body
  • A61F2/14—Eye parts, e.g. lenses, corneal implants; Implanting instruments specially adapted therefor; Artificial eyes
  • A61F2/16—Intraocular lenses
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
  • A61F2/02—Prostheses implantable into the body
  • A61F2/14—Eye parts, e.g. lenses, corneal implants; Implanting instruments specially adapted therefor; Artificial eyes
  • A61F2/16—Intraocular lenses
  • A61F2/1613—Intraocular lenses having special lens configurations, e.g. multipart lenses; having particular optical properties, e.g. pseudo-accommodative lenses, lenses having aberration corrections, diffractive lenses, lenses for variably absorbing electromagnetic radiation, lenses having variable focus
  • A61F2/1616—Pseudo-accommodative, e.g. multifocal or enabling monovision
  • A61F2/1618—Multifocal lenses
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
  • A61F2/02—Prostheses implantable into the body
  • A61F2/14—Eye parts, e.g. lenses, corneal implants; Implanting instruments specially adapted therefor; Artificial eyes
  • A61F2/16—Intraocular lenses
  • A61F2/1613—Intraocular lenses having special lens configurations, e.g. multipart lenses; having particular optical properties, e.g. pseudo-accommodative lenses, lenses having aberration corrections, diffractive lenses, lenses for variably absorbing electromagnetic radiation, lenses having variable focus
  • A61F2/1648—Multipart lenses
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
  • A61F2/02—Prostheses implantable into the body
  • A61F2/14—Eye parts, e.g. lenses, corneal implants; Implanting instruments specially adapted therefor; Artificial eyes
  • A61F2/16—Intraocular lenses
  • A61F2/1613—Intraocular lenses having special lens configurations, e.g. multipart lenses; having particular optical properties, e.g. pseudo-accommodative lenses, lenses having aberration corrections, diffractive lenses, lenses for variably absorbing electromagnetic radiation, lenses having variable focus
  • A61F2/1654—Diffractive lenses
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B5/00—Optical elements other than lenses
  • G02B5/18—Diffraction gratings
  • G02B5/1876—Diffractive Fresnel lenses; Zone plates; Kinoforms
  • G02B5/189—Structurally combined with optical elements not having diffractive power
  • G02B5/1895—Structurally combined with optical elements not having diffractive power such optical elements having dioptric power
• • G—PHYSICS
  • G02—OPTICS
  • G02C—SPECTACLES; SUNGLASSES OR GOGGLES INSOFAR AS THEY HAVE THE SAME FEATURES AS SPECTACLES; CONTACT LENSES
  • G02C7/00—Optical parts
  • G02C7/02—Lenses; Lens systems ; Methods of designing lenses
• • G—PHYSICS
  • G02—OPTICS
  • G02C—SPECTACLES; SUNGLASSES OR GOGGLES INSOFAR AS THEY HAVE THE SAME FEATURES AS SPECTACLES; CONTACT LENSES
  • G02C7/00—Optical parts
  • G02C7/02—Lenses; Lens systems ; Methods of designing lenses
  • G02C7/024—Methods of designing ophthalmic lenses
  • G02C7/028—Special mathematical design techniques
• • G—PHYSICS
  • G02—OPTICS
  • G02C—SPECTACLES; SUNGLASSES OR GOGGLES INSOFAR AS THEY HAVE THE SAME FEATURES AS SPECTACLES; CONTACT LENSES
  • G02C7/00—Optical parts
  • G02C7/02—Lenses; Lens systems ; Methods of designing lenses
  • G02C7/04—Contact lenses for the eyes
• • G—PHYSICS
  • G02—OPTICS
  • G02C—SPECTACLES; SUNGLASSES OR GOGGLES INSOFAR AS THEY HAVE THE SAME FEATURES AS SPECTACLES; CONTACT LENSES
  • G02C7/00—Optical parts
  • G02C7/02—Lenses; Lens systems ; Methods of designing lenses
  • G02C7/04—Contact lenses for the eyes
  • G02C7/041—Contact lenses for the eyes bifocal; multifocal
  • G02C7/042—Simultaneous type
• • G—PHYSICS
  • G02—OPTICS
  • G02C—SPECTACLES; SUNGLASSES OR GOGGLES INSOFAR AS THEY HAVE THE SAME FEATURES AS SPECTACLES; CONTACT LENSES
  • G02C7/00—Optical parts
  • G02C7/02—Lenses; Lens systems ; Methods of designing lenses
  • G02C7/04—Contact lenses for the eyes
  • G02C7/041—Contact lenses for the eyes bifocal; multifocal
  • G02C7/044—Annular configuration, e.g. pupil tuned
• • G—PHYSICS
  • G02—OPTICS
  • G02C—SPECTACLES; SUNGLASSES OR GOGGLES INSOFAR AS THEY HAVE THE SAME FEATURES AS SPECTACLES; CONTACT LENSES
  • G02C7/00—Optical parts
  • G02C7/02—Lenses; Lens systems ; Methods of designing lenses
  • G02C7/06—Lenses; Lens systems ; Methods of designing lenses bifocal; multifocal ; progressive
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B3/00—Simple or compound lenses
  • G02B3/02—Simple or compound lenses with non-spherical faces
  • G02B3/08—Simple or compound lenses with non-spherical faces with discontinuous faces, e.g. Fresnel lens
• • G—PHYSICS
  • G02—OPTICS
  • G02C—SPECTACLES; SUNGLASSES OR GOGGLES INSOFAR AS THEY HAVE THE SAME FEATURES AS SPECTACLES; CONTACT LENSES
  • G02C2202/00—Generic optical aspects applicable to one or more of the subgroups of G02C7/00
  • G02C2202/20—Diffractive and Fresnel lenses or lens portions

Definitions

• the present invention relates to diffractive lenses for vision correction, and particularly to diffractive lenses for therapeutic vision correction at at least distance and near vision correction suitable for use with a variety of vision correction applications, such as intraocular implants (IOLs), contact lenses, or spectacle (eyeglass) lenses.
• the invention further relates to a method for providing such diffractive lenses.
• Multiorder diffractive (MOD) lenses are useful for bringing a plurality of spectral components of different wavelengths to a common focus, and are described in U.S. Patent No. 5,589,982.
• the MOD lens has a structure of multiple annular zones having step heights defining zone boundaries, which diffract light at different wavelengths into different diffractive orders to a common focus.
• viewing light of multiple different wavelengths through non-MOD diffractive multifocal lens can appear blurry since different wavelengths of light are in focus at different distances.
• the MOD lenses correct for this problem, but does not provide two different focal distances, e.g., near and distant, useful for providing therapeutic bifocal corrective ophthalmic lenses.
• Non-MOD diffractive lenses can have a diffractive profile for diffracting different orders of light at any given wavelength to different focal distances.
• Such non-MOD multifocal diffractive lenses may be provided on a single lens surface or have zones divided over different surfaces of a lens. Examples of non-MOD multifocal lens are described in U.S. Patent Nos. 5,017,000; 5,144,483; 3,004,470; 4,340,283; and 4,210,391. Still other non- MOD multifocal lenses have an additional non-MOD diffractive surface correcting for chromatic aberration, as in U.S. Patent No. 5,117,306.
• refractive power can be added to the lens for distance vision correction.
• Hybrid refractive-diffractive lenses are described, for example, in U.S. Patent Nos. 5,229,797; 5,104,212; 6,120,148; 5,760,871; and 5,116,111. These hybrid refractive- diffractive lenses are thicker than non-refractive diffractive lenses due to additional lens material needed to add curvature to the lens body. However, thickness reduction is often desirable in ophthalmic applications, such as contact lenses and IOLs. Thus, it would be desirable to provide a diffractive ophthalmic lens for bifocal applications which can utilize diffractive structures without the need to rely on refractive power for distance vision correction.
• MOD multiorder diffractive structure
• non-MOD diffractive structure in which the combination of the two diffractive structures provides a bifocal lens having a base power for distance vision correction and an add power for near vision correction.
• Another feature of the present invention is to provide diffractive lenses for at least near and distance vision correction which may be adapted for use in a variety of vision correction applications, including contact lenses, intraocular implants (IOL), and spectacle lenses.
• IOL intraocular implants
• a further feature of the present invention is to provide diffractive lenses for vision correction having a MOD structure and a non-MOD diffractive structure, in which the non- MOD diffractive structure can be one that is harmonic and without sharp edges.
• the present invention embodies a lens having a first diffractive structure, referred to herein as a wavefront splitting diffractive structure (WSD), for splitting light into two or more diffractive orders to different focus distances or ranges, and a second diffractive structure, referred to as a multiorder diffractive structure (MOD), for diffracting light of different wavelengths in a plurality of different diffractive orders to a common focus distance or range.
• WSD wavefront splitting diffractive structure
• MOD multiorder diffractive structure
• the first and second diffractive structures in combination provide the lens with at least distance and near vision correction.
• the first and second diffractive structures may be combined on the same surface or located on different surfaces of the lens.
• light incident the lens is diffracted by the first diffractive structure and then by the second diffractive structure, or vice versa depending on the order of such structures in the lens, or by a single diffractive structure of the lens having a profile that combines the first and second diffractive structures.
• the WSD structure may be any diffractive surface that that has high diffraction efficiency in two or more orders to different focus distances or ranges.
• the WSD structure may have blazed (i.e., sawtooth), sinusoidal, sinusoidal harmonic, square wave, or other shape profile.
• the WSD structure has two different optical powers for each of its diffractive orders, and the MOD structure is of one optical power.
• the base power of the lens is provided by the combination of the optical power of the MOD structure with the optical power of the WSD structure in one of its orders, and the add power of the lens is provided by the combination of the power of the MOD structure with the power of the WSD structure in its other order.
• the WSD structure has three diffractive orders to add an intermediate power when combined with the power of the MOD structure for intermediate distance vision correction between near and distance vision correction. More than three different orders may similarly be provided to the WSD structure in multifocal applications having more than three vision correction distances.
• an optical element such as a substrate or coating, may be provided on the surface having the MOD structure to provide a smooth outer surface.
• the MOD structure of the lens is characterized by multiple zones which define zone boundaries at which light incident on this structure experiences an optical phase shift, and diffracts light of each of the wavelengths in a different diffractive order, m, such that the magnitude of m is greater than or equal to 1, to the same focus.
• the MOD structure is described in more detail in U.S. Patent No. 5,589,982.
• a sinusoidal harmonic WSD structure is defined as a structure having a plurality of zones that is continuous within each of the zones and at the boundaries between zones, thereby providing such structure without the sharp edges typical of blazed (i.e., sawtooth), or square wave diffractive structures.
• Each of the zones of the sinusoidal harmonic WSD structure can have radial locations characterized the equation:
• the present invention further provides a method for providing a bifocal ophthalmic lens by selecting a MOD structure for the lens in accordance with the needed base power of the lens, and then selecting a sinusoidal harmonic WSD structure for the lens, in which the base power for distance vision correction and add power for near vision correction are in accordance with a combination of the MOD and WSD structures.
• a trifocal or other multifocal lens may similarly be provided for one or more intermediate vision correction distances between the near and distance vision correction.
• refractive power optionally may be added to the lens to supplement or add to the base power already present by benefit of the MOD structure of the lens.
• refractive power may provide the base power of the lens instead of a MOD structure.
• a multifocal lens has a sinusoidal harmonic WSD structure, a lens body shaped to provide refractive base power, and no MOD structure.
• Astigmatism may further be corrected by the lens in one or more of its diffractive structures and/or by adding refractive curvature to one or more of the surfaces with such diffractive structures.
• the lenses of the present invention may be used in a variety of ophthalmic applications, such as a contact lens, a spectacle lens, or the lens of an intraocular implant (IOL), or other optics useful for vision correction of the eye.
• a contact lens application it is advantageous to use of a WSD structure that is a sinusoidal harmonic, since the edges of the structure are so smooth that the structure can be located directly on the lens' surface which will contact the eye (or the inner eye lid), and thus worn comfortably by the contract lens user without undesirable irritation that would otherwise be caused by the presence of sharp edges.
• a lens having such a sinusoidal harmonic WSD structure can be easier to manufacture and at lower cost in application since the surface does not require to be smoothed by addition of coatings or substrates.
• the present invention may also embody a diffractive optical element with at least one sinusoidal harmonic diffractive structure in ophthalmic or non-ophthalmic applications.
• FIGS. IA and IB are plan views of the front and back surfaces, respectively, of a first embodiment multiorder diffractive lens of the present invention having a wavefront splitting diffractive (WSD) structure on the front surface and a multiorder diffractive (MOD) structure on the back surface of the lens, in which FIG. IA shows the annular regions of the WSD structure on the front lens surface, and FIG. IB shows the annular regions of the MOD structure on the back lens surface;
• WSD wavefront splitting diffractive
• MOD multiorder diffractive
• FIG. 1C is a sectional view through the lens of FIGS. IA and IB showing the side profile of the WSD and MOD structures on the front and back surfaces, respectively;
• FIG. ID is sectional view of an alternative lens of the first embodiment in which the WSD and MOD structures are profiles on the back and front surfaces, respectively, where FIGS. IA and IB represent view of the back and front surface of this alternative lens;
• FIG. 2A is a sectional view of a lens of FIG. 1C with addition of an optical element integrated with the back surface of the lens to provide a smooth back surface;
• FIG. 2B is a sectional view of a lens of FIG. ID with addition of an optical element integrated with the back surface of the lens to provide a smooth back surface;
• FIG. 3A is a sectional view of a lens of FIG. 1C with addition of an optical element integrated with the front surface of the lens to provide a smooth front surface;
• FIG. 3B is a sectional view of a lens of FIG. ID with addition of an optical element integrated with the front surface of the lens to provide a smooth front surface;
• FIG. 4A is a sectional view of a lens of FIG. 1C with addition of optical elements integrated with the front and back surfaces of the lens to provide smooth front and back surfaces;
• FIG. 4B is a sectional view of a lens of FIG. ID with addition of optical elements integrated with the front and back surfaces of the lens to provide smooth front and back surfaces;
• FIGS. 5 A, 5B, 5C, 5D, 5E and 5F are optical ray diagrams for examples of different ones of the lens of the present invention for bifocal applications;
• FIGS. 6 A and 6B are optical ray diagrams of different ones for examples of the lens of me present invention for trifocal applications;
• FIG. 7 is a cross sectional view of a second embodiment multiorder diffractive lens of the present invention having a first surface with WSD structure, a second surface with a MOD structure, and the lens body has curvatures providing refractive power to the lens;
• FIG. 8A is a cross sectional view of a third embodiment multiorder diffractive lens of the present invention in which the WSD and MOD structures are combined into a single profile along the front surface of the lens and the back surface has no diffractive structure;
• FIG. 8B is a cross sectional view of an alternative third embodiment multiorder diffractive lens of the present invention in which the WSD and MOD structures are combined into a single profile along the back surface of the lens and the front surface has no diffractive structure;
• FIG. 8C is a sectional view of a lens of FIG. 8B with addition of an optical element integrated with the back surface of the lens to provide a smooth back surface;
• FIG. 9 is a cross sectional view of a fourth embodiment multiorder diffractive lens of the present invention having WSD and MOD structures combined into a single diffractive structure along the back surface of the lens, where the lens body has curvature providing refractive power to the lens and an optical element is integrated with the front surface of the lens to provide a smooth front surface;
• FIGS. 1OA and 1OB are plan views of the front and back surfaces, respectively, of a multiorder diffractive lens similar to FIGS. IA and IB, in which a sinusoidal harmonic WSD structure having a continuous smoothly varying profile is provided on the front surface of the lens, and a MOD structure is provided on the back surface of the lens;
• FIG. 1OC is a sectional view through the lens of FIGS. 1OA and 1OB;
• FIG. 11 is a graph of the optical path difference (OPD) in waves between periods 0 and 1 of a first example of a sinusoidal harmonic diffractive surface for the WSD structure of the lens of the present invention
• FIG. 12 is a graph of an example of the surface curvature (sag) versus radial position of the first example of the sinusoidal harmonic diffractive surface showing the non-sharp, i.e., substantially smooth, edges and the periodicity of the profile over the surface;
• FIGS. 13 and 14 and graphs similar to FIGS. 11 and 12, respectively, for a second example of a sinusoidal harmonic diffractive surface for the WSD structure of the lens of the present invention
• FIG. 17 is a cross-sectional view of lens having an example of a sinusoidal harmonic diffractive surface in the case of a curved surface
• FIG. 18 is a graph of the surface curvature (sag) versus radial position for the fourth example of a sinusoidal harmonic diffractive surface along the curved surface of FIG. 16.
• a lens 10 is shown having a front surface 12 and a back surface 13 on the sides of a single element lens body 14.
• the front surface 12 has a wavefront splitting diffractive (WSD) structure 16, and the back surface 13 has a multiorder diffractive (MOD) structure 17. Examples of the annular zone or regions of the WSD structure 16 and the MOD structure 17 are shown in FIGS. IA and IB, respectively.
• the curvature of the lens body 14 provides zero or near zero refractive power, and thus the lens in contact on IOL applications may be made very thin, such as, for example, 0.2-0.8 mm thick.
• the lens 10 diameter is in accordance with its particular ophthalmic application, contact, IOL, or spectacle.
• the lens in an IOL may have additional haptic or support structures as typical of IOLs, such as described, for example, in U.S. Patent Nos. 6,406,494, 6,176,878, 5,096,285, or U.S. Patent Application Publications Nos. 2002/0120329 Al, 2002/0016630 Al, 2002/0193876 Al, 2003/0014107 Al, or 2003/0018385 Al, or without typical haptic structures, as shown in U.S. Patent No. 4,769,033.
• the WSD structure 16 may be on the back surface 13, and the MOD structure 17 on the front surface 12, as shown in FIG. ID.
• the MOD structure 17 is described in U.S. Patent No. 5,589,982, which is herein incorporated by reference.
• the MOD structure has zones with step heights providing mainly or entirely the base power for distance vision correction in accordance with the eye of the lens user.
• the WSD structure 16 is a non-MOD lens which in combination with MOD structure 17 provides the add power of the lens 10 for near vision correction in accordance with the eye of the lens user.
• Any diffractive surface that can provide a WSD structure that has high diffraction efficiency in two or more orders (at the primary design wavelength) may be used.
• the WSD structure may have blazed (i.e., sawtooth), sinusoidal, sinusoidal harmonic, square wave, or other shape profile.
• the sinusoidal harmonic WSD structure is described later in more detail in connection with FIGS. 1 OA-18.
• Lens 10 may be composed of transmissive material, such as typically used in the manufacture of contacts, optic portion of IOLs, or spectacles (e.g., plastic, silicone, glass, or polymers typically used for the particular contact, IOL, or spectacle application).
• Typical processes providing diffractive optical surface such as etching, molding or direct diamond turning, may form the zones of the MOD and WSD structures on their respective surfaces of the lens.
• single point diamond turning machinery from Precitech, Inc. of Keene, New Hampshire may be used to machine any diffractive structure described herein on a substrate lens material to produce the desired profile along a lens surface, or to produce a mastering tool enabling replication (e.g., by molding) of such diffractive structure in producing the lenses.
• an outer surface along the side of lens 10 with a diffractive surface may need to be smooth.
• an optical element 18 with a smooth outer surface 19 is integrated with the back surface 13 of lens 10, as shown in FIGS. 2A and 2B for lens of FIGS. 1C and ID, respectively, or the front surface 12 of lens 10, as shown in FIGS. 3A and 3B for lens of FIGS. 1C and ID, respectively.
• Optical element 18 may be a substrate or coating (applied and cured) of an optically transparent material (e.g., plastic, silicone, glass, or polymers) having an index of refraction different from the index of refraction of the lens 10 material, such that light may properly be diffracted by the diffractive structures of the lens.
• Optical element 18 has a surface 20 shaped with the reverse profile of the diffractive surface to face that surface when attached to lens 10.
• optical element 18 represents a substrate, its surface 20 mates with such diffractive structured surface when bonded thereto (e.g. liquid adhesive), fused, or otherwise sealed together.
• the outer surfaces of both sides of lens 10 may need to be smooth.
• the front surface 12 and back surface 13 of the lens of FIGS. 1C and ID may be integrated with optical elements 18a and 18b, as shown in FIGS. 4A and 4B, respectively.
• Each optical element 18a and 18b has a smooth outer surface 19a and 19b, respectively, and a surface 20a and 20b, respectively, facing its respective diffractive structured surface. If needed, outer surface 19 of the optical element 18 of FIGS. 2A, 2B, 3 A, or 3B, or surface 19a and 19b of optical elements 18a and 18b of FIGS.
• optical element 18, or 18a and 18b may need to be processed (e.g., cut and/or ground) to obtain a smooth surface suitable for their ophthalmic application.
• Integration of optical element 18, or 18a and 18b, to provide smooth surface(s) to a diffractive surface profile may be as described, for example, in U.S. Patent Nos. 5,129,718, 5,760,871 or 5,104,212, or in U.S. Published Application No. 2001/0018012.
• the lens 10 having a MOD structure and WSD structure which combine to provide bifocal vision correction is illustrated in the following two examples.
• an ophthalmic lens prescription requires a correction of -7 diopters (D) for distance vision, with a +2 diopters (D) add power for near vision.
• D diopters
• D +2 diopters
• the lens will consist of a MOD structure 17 with the required distance power on one side (i.e., along surface 12 or 13) of a thin substrate providing the lens body 14, and with a WSD structure 16 with a blazed surface, operating primarily in the 0 and +1 orders, on the other side (or surface).
• the selected design wavelength Ao 555 nm (peak of photopic response).
• the height (h) of the zones is given by
• Equation (4) of the above-incorporated patent. where/) is the MOD number of the MOD structure as discussed in above-incorporated U.S. Patent, and ni ens is the refractive index of the lens body material, and n me diu m is the refractive index of a medium, such as air or a substrate 18, 18a or 18b.
• the WSD structure 16 on the other side (or surface) of the substrate providing the lens body 14 has a power equal to the add power ⁇ a dd-
• the radial locations of the diffractive zones are
• the zone radii within a clear aperture diameter of 10 mm are: • Wavefront splitting structure (+2 D)
• the height of the zones for the WSD structure is selected such that a maximum of one-half of a wavelength of optical path difference (OPD) is introduced. This will result in diffraction efficiencies of 40.5% in both the 0 and +1 diffraction orders.
• OPD optical path difference
• the 0 order combines with the MOD structure to produce the distance image (since the WSD surface adds no power to the lens), while the +1 order combines with the MOD structure to produce the near image.
• the zone height is h - V 2
• This example has the same ophthalmic prescription (-7 D distance power, with a +2 D add power) as Example 1, but uses a WSD structure 16 having a square- wave diffractive surface.
• n med ⁇ um ( ⁇ o) 1.0.
• the radial locations of the diffractive zones of the square-wave WSD structure 16 on the other side (surface) of the substrate providing the lens body 14 are:
• the zone radii within a clear aperture diameter of 10 mm are: • Square-wave diffractive surface ( ⁇ 1 D)
• the height of the square- wave diffractive surface over half of each diffractive zone is selected such that one-half of a wavelength of optical path difference (OPD) is introduced. This results in diffraction efficiencies of 40.5% in both the +1 and -1 diffraction orders.
• OPD optical path difference
• FIGS. 5A-5F examples of optical ray diagrams for different ones of lens 10 are shown.
• the diagrams would also include the optics of the eye, such as in the case of a spectacle (i.e., lens 10 at a distance from the eye), IOL (i.e., lens 10 within the eye), or contact (i.e., lens 10 on the outer surface of the cornea).
• FIGS. 5A-5D show the use of different power WSD and MOD structures to provide the same bifocal prescription, but in different orders.
• the lens has -5D near (add) power in the +1 order and -7D distance (base) power in the 0 order resulting from a +2D power WSD structure 16 having a blazed profile (0, +1 order) and a -7D power MOD structure 17.
• the lens has a -2D power WSD structure 16 with a blaze profile and a -5D power MOD structure 17.
• the lens of FIG. 5C provides +4D distance (base) power in the 0 order and +6D near (add) power in the +1 order using a +2D power WSD structure 16 and a +4D power MOD structure 17.
• FIGS. 5E and 5F show a lens 10 having a WSD structure 16 with a square wave profile (+1, -1 orders) and different power MOD structures 17 of -6D and a +5D powers, respectively.
• the FIG. 5E lens results in a - 5D near (add) power in the +1 order, and -7D distance (base) power in the -1 order.
• the FIG. 5F lens results in a +4D distance (base) power in the -1 order, and a +6D near (add) power in the +1 order.
• different profile shapes on the WSD structured surface can be selected which when combined with a MOD structured surface, which is selected in accordance with the desired base power, provides a bifocal lens 10 with the desired near and distance vision correction.
• Examples 1 and 2 are illustrated for example by FIG. 5A and FIG. 5E, respectively.
• a sinusoidal profile could also be used, which like a square wave of FIGS. 5E and 5F, splits the light between +1 and -1 orders.
• the diffractive power of the WSD structure 16 will be a full add power, while a split in +1 and -1 orders will half the add power, since this diffractive surface contributes power to both near and distant images.
• a diffractive surface with a +1 and -1 split has larger and fewer zones and less possible chromatic aberration, since power is less in each zone in contrast with a diffractive surface with 0 and +1 orders.
• a trifocal lens may also be made with lens 10 by selecting a WSD structure 16 in which the modulation depth of a sinusoid profile is changed slightly, resulting in equal energy in the +1, 0 and -1 orders.
• FIGS. 6A and 6B show such a WSD structure 16 with different power MOD structures of -6D and +5D, respectively.
• the FIG. 6A lens provides a -7D distance power in the -1 order, -6D intermediate power in the 0 order, and -5D near power in the +1 order.
• the FIG. 6B lens provides +4D distance -power in the -1 order, +5D intermediate power in the 0 order and +6D near power in the +1 order.
• a WSD structure with more than three orders may be used to provide other multifocal lenses other than bifocal or trifocal.
• lens 10 of FIG. 1C is shown in FIGS. 5A-5D or 6A-6B, but any of the lens of FIGS. ID, 2A, 2B, 3A, 3B, 4A, 4B, 5A, 5B, 7A or 7B may be used by selection of power and profile for their respective WSD and MOD structures in accordance with the examples of .FIGS. 5A-5D or 6A-6B. Different powers may be used for the WSD and MOD structure of FIGS. 5A-5D or 6A-6B to provide different prescriptions as needed for the user of the lens.
• the number of rings shown on diffractive structures in these figures and other figures are illustrative, different number of rings, spacing, and heights may be used.
• the lens 10 has little or no refractive power.
• refractive power may be provided by adding curvature to lens body 14a of lens 10a, as shown in FIG. 7.
• Lens 10a is similar to lens 10 in that WSD structure 16 and MOD structure 17 are provided on the front surface 12a and back surface 13 a, respectively.
• the WSD structure 16 and MOD structure 17 may be provided on the back surface 13a and front surface 12a, respectively.
• An optical element 18 may be integrated with one or both of the surfaces of the lens 10 to provide a lens or lens system with one or two smooth outer surfaces, as described earlier.
• the refractive power of lens 10a combines with the MOD structure 17 and WSD structure 16 to affect the base power of the lens for distance correction.
• lens 10a since the MOD structure already contributes to base power of lens 10a, the amount of refractive power needed is much less than if the lens lacked the MOD structure as in prior art hybrid refractive diffractive lenses. Thus, lens 10a although thicker than lens 10, may be made much thinner by the use of the MOD structure 17 than diffractive lens with refractive power of equivalent power without a MOD structure.
• the WSD structure 16 and MOD structure 17 may be combined into a single diffractive structure 21 along a surface 22 of lens 10, where FIG. 8 A shows this surface 22 along the front of the lens, and FIG. 8B shows this surface on the back of the lens.
• An optical element 18 may be integrated with diffractive structure 21 to provide a smooth outer surface 19, as described earlier.
• lens 10 of FIGS. 8A-8C has little or no refractive power, optionally curvature may be added to the lens body 14b to provide lens 10b as shown in FIG. 9.
• the lens 10b is illustrated with optical element 18c with smooth surface 19c in which optical element 18c is integrated with the diffractive structure 21.
• lens 10b may be provided without optical element 18c.
• the diffractive structure 21 represents a superposition of a WSD structure 16 superimposed on a MOD structure 17, or vice versa.
• the same prescription of FIGS. 5A- 5F and 6A-6B may be provided using a single surface 22.
• Optical element 18 when integrated in lens 10 becomes part of lens 10, and similarly, optical elements 18a and 18b of FIGS. 4A, 4B when integrated with lens 10 becomes part of lens 10. Also, optical element 18c of FIG. 9 becomes part of lens 10b when integrated thereto.
• lens 10, 10a and 10b are shown as a single element lens body 14, 14a, and 14b, respectively, the lens body may be a single element or composed of multiple optical elements integrated together.
• a single layer is illustrated for optical element 18, 18a, 18b, and 18c in the figures, the layer may be a single or multiple layers of optical elements (e.g., substrates and/or coatings).
• Astigmatism may also be corrected in the lens 10, 10a, and 10b by use of non-circular zones (hyperbolic or elliptical) in one or more of the WSD structure 16, MOD structure 17, or diffractive structure 21, such as described in U.S. Patent No. 5,016,977 for non-MOD diffractive structures.
• the zone spacing is different in the horizontal and vertical dimensions of the lens, rather than by the same dimension as shown in the above Examples 1 and 2.
• the lens may also correct astigmatism by adding refractive curvature to the profile of one or more of the surfaces with such diffractive structures.
• astigmatism may be corrected in lens 10, 10a, and 10b by refraction in the lens body as used in typical refractive lenses.
• the WSD structure 16 may be a sinusoidal harmonic (or periodic) diffractive structure, a particular type or class of sinusoidal profile wavefront splitting diffractive structures. (Although described below in cosine terms, the surface may be equivalently expressed in sine and/or cosine terms).
• FIGS. 1OA, 1OB, and 1OC show an example of lens 10 similar to FIGS. IA, IB and 1C, respectively, but with WSD 16 provided by a sinusoidal harmonic WSD structure 16a on the front surface of the lens, and a MOD structure 17 provided on the back surface of the lens.
• WSD 16a and MOD 17 may be on the back and front surfaces, respectively, of the lens.
• the sinusoidal harmonic WSD structure provides a continuous, smoothly varying diffractive wavefront splitting surface both within zones and along boundaries between zones, as best shown in FIG. IOC in which the scale of the surface heights is exaggerated for purposes of illustration. This provides boundaries (or transitions) between zones which are not abrupt in contrast to the discontinuous zone boundaries of blazed diffractive structures (as best shown for example by WSD 16 of FIG. 1C) or square wave diffractive structures.
• the sinusoidal harmonic WSD structure 16a provides the add power in +1, -1, or +1, 0, -1 diffractive orders.
• the sinusoidal harmonic WSD structure may be used instead of a square wave WSD diffractive structure having +1, -1 orders such as described earlier in Example 2.
• Other diffractive order may also be provided by the sinusoidal harmonic WSD structure.
• the sinusoidal harmonic WSD structure may be used in lens 10 of FIGS. 2A, 2B, 3 A, 3B, 4A, 4B, 8A, 8B, or 8C, or used in providing lens 10a and 10b of FIGS. 7 and 9, respectively.
• the sinusoidal harmonic WSD structure is particularly useful in providing a lens of the present invention when a continuous and smoothly varying surface is desirable. Optical equations expressing the sinusoidal harmonic WSD structure will now be described.
• ⁇ can be considered as the fractional position (O ⁇ l) within the diffractive zone.
• the surface is continuous and continuously differentiable within each zone and at the boundaries between zones, since
• a rotationally symmetric diffractive lens is usually represented by a phase function consisting of a power series in r, the radial coordinate, e.g.,
• the transmission function for the element is a phase function:
• the periodicity of z means that t( ⁇ ) may be expanded as a Fourier series t ⁇ )- ⁇ a m e' 2!m ⁇
• the sinusoidal harmonic diffractive surface is designed by choosing a number of terms (j max ) and finding values of a / and ⁇ j , such that desired values (or as close to the desired values as possible) of particular ⁇ m are produced.
• this may be done numerically using a numerical optimization routine, such as damped least squares or simplex.
• a suitable error function also referred to as merit function, objective function
• many error functions are possible; one for example is
• ⁇ m is the diffraction efficiency in order m
• ⁇ m is the target (desired) efficiency in order m
• a ⁇ m is the tolerance on the efficiency for order m.
• the tolerance acts as a weighting factor in the error function. The sum is over all orders m with a target efficiency. The optimization routine will try to minimize the value of M.
• the distribution of diffraction efficiencies is determined by the form of the individual zone profile (i.e., the a j and ⁇ j); the locations of the diffracted orders depend upon the particulars of the zone locations.
• the sinusoidal harmonic diffractive structure may equivalently be described by optical path difference (OPD).
• OPD optical path difference
• the optical path difference (OPD) introduced by a surface profile, in units of the design wavelength ⁇ o, is given by
• the sinusoidal harmonic WSD structure has two orders 1 and -1 having equal efficiencies, and the number of terms j max has been selected to equal 9.
• ⁇ _ ⁇ 0.4
• ⁇ ⁇ 0.392
• OPD( ⁇ ) shown earlier the amplitude and phase are as follows:
• FIG. 11 shows a single period of the profile of this example, where the vertical axis shows the optical path difference (OPD) in waves introduced by the surface.
• OPD optical path difference
• the sinusoidal harmonic WSD structure of this example may be used as the WSD structure in the lens of earlier example (labeled Example 2) for the ophthalmic prescription -7 D distance power with a +2 D add power, where a sinusoidal harmonic WSD structure is desirable having equal diffraction efficiencies in the +1 and -1 diffractive orders.
• the sinusoidal harmonic WSD structure has two orders 1 and -1 having different efficiencies, and the number of t ⁇ rmj max has been selected to equal 9.
• T ⁇ 1 0.475
• ⁇ _ x 0.324
• results in diffraction efficiencies of ⁇ ⁇ 0.463
• ⁇ . ⁇ 0.307.
• OPD( ⁇ ) shown earlier the amplitude and phase are as follows:
• FIG. 13 shows a single period of the profile of this example, where the vertical axis shows the optical path difference (OPD) in waves introduced by the surface.
• OPD optical path difference
• the resulting surface is shown FIG. 14.
• the difference in this example is that the two images for each order are weighted in the ratio 0.463:0.307, rather than the equal weighting of the previous example.
• the sinusoidal harmonic WSD structure of this example may be used as the WSD structure in the lens of earlier example (labeled Example 2) for the ophthalmic prescription -7 D distance power with a +2 D add power, where a harmonic WSD structure is desirable having unequal diffraction efficiencies in the +1 and -1 diffractive orders.
• the sinusoidal harmonic WSD structure has three orders 1, -1, and 0 having different efficiencies, and the number of term J m0x has been selected to equal 9.
• FIG. 15 shows a single period of the profile, where the vertical axis shows the optical path difference (OPD) in waves introduced by the surface.
• OPD optical path difference
• the lens phase function results in a lens with three powers: +1 D, 0 D, and -1 D.
• ⁇ o 555 nm
• n refractive index
• the sinusoidal harmonic WSD structure of this example may be used to provide the trifocal lens as described earlier in connection with FIGS. 6A and 6B.
• the previous three sinusoidal harmonic WSD examples were implemented on flat (planar) substrates. It is also possible to use the sinusoidal harmonic surface on a surface with refractive power, i.e., a curved surface.
• a surface with refractive power i.e., a curved surface.
• the sinusoidal harmonic WSD structure provides the add power of the lens and either a MOD structure, or the lens body's refractive curvature provides the base power of the lens.
• the base power of the lens may be provided by a combination of a MOD structure and refractive curvature of the lens body, if desirable.
• cosine terms are shown above in describing the sinusoidal harmonic diffractive surface, such te ⁇ ns may be sine terms, or a combination of cosine and sine terms, to define equivalent surfaces. This is evident by the following example.
• te ⁇ ns may be sine terms, or a combination of cosine and sine terms, to define equivalent surfaces. This is evident by the following example.
• a H 4a c 2 + a] + 2a c a s sm( ⁇ s - ⁇ c ) ⁇ H — tan -1 ⁇ *c Si ⁇ ( ⁇ c)- a , ⁇ S ⁇ ,)
• the sinusoidal harmonic WSD structure is referred to earlier as a type or class of sinusoidal profiles, since it may be expressed equivalently in cosine and/or sine terms.
• the edges are particularly smooth, and thus such structure is useful in ophthalmic (e.g., contact lens) or non-ophthalmic applications where smooth edges are desirable.
• one or more sinusoidal harmonic diffractive structures may be provided on the body of an optical element with or without a MOD structure, and with or without refractive curvature along the body.

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